Method and apparatus for manufacturing an absorbent article

ABSTRACT

The invention relates to a method of manufacturing an absorbent article (144), wherein the speed of a part (7b) of a continuously moving web (1) comprising a topsheet (121), backsheet (123), core (120) or any combination thereof, is periodically varied, while maintaining a constant speed of the upstream (3) and downstream (5) parts of the web (1). The method comprises feeding the web (1) past rotating transportation rollers (13, 15) which are oscillated parallel to the web (1) in the direction of transportation (F) and opposite to the direction of transportation (F). Three web sections (7a, 7b, 7c) are during oscillation of the transportation rollers (13, 15) maintained in a mutually parallel relationship. Translation means (77) and rotation balancing means (63, 63&#39;) allow the transportation rollers (13, 15) to be driven at high speeds and low variations in torque. The strain exerted on the web (1) remains relatively low and is limited to the inertia forces that act on the web (1).

FIELD OF THE INVENTION

The invention relates to a method of making an absorbent articlecomprising a liquid pervious topsheet, a liquid-impervious backsheet andan absorbent core interposed between the topsheet and the backsheet, themethod comprising the steps of:

a feeding a web, comprising the topsheet, the backsheet or the core or acombination thereof along a stationary frame, along an upstreamtrajectory, a downstream trajectory, and an intermediate trajectorycomprised between the upstream trajectory and the downstream trajectory,the web having along the upstream trajectory and along the downstreamtrajectory a substantially constant speed of transport, the upstream andthe downstream trajectory being substantially stationary relative to theframe,

b running the web along an upstream and a downstream transport rollerthat are periodically displaceable, and

c periodically displacing the transport rollers around a stationaryequilibrium position.

The invention also relates to an apparatus for carrying out the methodaccording to the invention.

BACKGROUND OF THE INVENTION

It is well known in the art to produce absorbent articles such asdisposable diapers by combining a liquid pervious topsheet, a liquidimpervious backsheet and an absorbent core to form a continuously movingweb. In the American patent U.S. Pat. No. 4,081,301, a method isdescribed to continuously attach discrete lengths of elastic ribbon tothe moving web by feeding a continuous elastic ribbon in a pre-stretchedstate into the nip in which the topsheet and backsheet are joined aroundthe absorbent core. The continuous elastic ribbon which runs along thelongitudinal sides of the web, is provided with adhesive atpre-determined intervals. After cutting the web transversely to formindividual diapers, parts of the elastic ribbons that have not beenprovided with glue, retract to their relaxed state to be positionedwithin the periphery of the topsheet and the backsheet, withoutgathering the topsheet and the backsheet in the unattached areas.

From the European Patent EP-A-0 256 869 it is known to pass a continuousfibrous web having multiple corrugations, under a powder depositingorifice to deposit an absorbent powder, such as a water-swellablepolymeric material in the corrugations. After passing under the powderdepositing orifice, the web is fed to a motion changing device to changethe movement of the web from continuous to intermittent motion. Themotion changing device comprises a vertically oscillating roller, underwhich the web is passed. When the roller travels downwardly, the web atthe upstream side of the roller is stored along the extra path lengthcreated by the downward movement, the motion of the web downstream ofthe roller being stopped.

The above method has as a disadvantage that all the web downstream ofthe oscillating roller is accelerated and decelerated by thereciprocation of the vertical roller. The interruption of movement ofthe web may interfere with the functioning of applicator devices locateddownstream of the vertical roller. Also the accelerations acting on theweb by changing the speed of all of the web downstream of the verticalroller, results in a relatively high strain being exerted on the web.

From U.S. Pat. No. 4,399,905 an apparatus for forming a stack ofarticles is known, in which a flight of grippers are mounted on anendless belt. The belt is looped around transport members, which arereciprocated so that a part of the belt is cyclically stopped, at acontinuous drive of the belt. By moving the transport members againstthe direction of transport of the belt, with the transport velocity, thespeed of the belt relative to stationary frame of the stacker isstopped.

A disadvantage of the above apparatus is that the velocity of thereciprocating transport member needs to equal the speed of transport ofthe belt for a part of the belt to become stationary. Furthermore, thepath length of the part of the belt hat extends between the transportmember and a stationary roller, changes upon reciprocation of thetransport member. Hence, the known apparatus can only be used incombination with a chain or a toothed belt but not in combination with aflat web or relatively low strength.

The European Patent Application EP-A-0 364 087 discloses an applicatordevice for applying layers of material generally transversely across anelongated web. The elongated web moves continuously through the devicein the machine direction at a predetermined web speed. The machinedirection corresponds to the longitudinal direction of the web. Thedevice comprises two transport members which each deflect the webthrough 90°, in the plane of the web. A transverse web portion ofconstant length, extending perpendicular to the machine direction, iscomprised between the transport members, which are formed by air bars.The transport members are mounted on a can which can be reciprocated inthe machine direction.

When the transport members are moved in the transport direction of theweb, at a speed which equals the web speed, the web portion between thetransport members is stationary relative to the transport members. Thetransverse web portion is in this case stationary in the directionperpendicular to the machine direction, i.e. in the cross machinedirection. A rotating applicator wheel, having a tangential speed whichequals the linear speed of the air bars, can contact the transverse webportion to attach a layer of material. Upon reversal of the movement ofthe air bars against the web's feed direction, the transverse webportion is accelerated past the air bars to the web's downstream side.The device can be used to apply layers of liquid such as ink, paint oradhesive or layers of film, paper, nonwovens or tape to webs. The devicewas found particularly suitable for applying elastic material,reinforcing layers, fasteners, moisture barriers etc. to a polymeric webadapted to subsequently be cut during the manufacture of disposablegarments such as diapers.

Although the above device is effective in changing the speed of only apre-determined portion of a web, the upstream and downstream parts beingrun at constant speed, the device introduces to the web portion a netspeed component which is parallel to the direction of transport of theweb. An applicator device is therefore necessary that moves with thespeed of displacement of the air bars parallel to the transportdirection, for the application of the transverse features to the web.

For completely stopping of the movement of the web relative to thetransport members, the transport members need to travel with speed oftransport, opposite to the incoming web. Especially at high web speeds,the transport members will be subject to large accelerations.

Another disadvantage of the known device, is that the centre line of thedownstream part of the web is displaced in the cross-machine direction,with respect the centre line of the upstream part of the web.

Furthermore, the above apparatus introduces significant stress to theweb as it is pulled over two non-rotating bars such that friction forcesare exerted which are proportional to the exponential value of thecoefficient of friction.

From the European Patent application EP-A-0 284 652 it is known tosupply tensioned elastic ribbons transversely to a continuously movingweb at a high speed. A number of applicator heads are mounted on arotatable vertical shaft, each applicator head being connected to aradial arm. Upon rotation of the shaft, the arms pass over the movingweb. At the position when a radial arm extends perpendicular to the weband has a tangential velocity equal to the linear web speed, apre-stretched elastic is fed from the applicator head. A rotating anvil,which has a circumferential velocity equal to the linear web speed tominimise the shearing forces, contacts the applicator head uponattachment of the elastic.

The above apparatus can, because of its multiple arms, attach transverseparts to the moving web at high speed and exerts a low tension on theweb. However, the speed of the whole web is constant. For application oftransverse parts to a web that require for instance, due to theircomplexity, momentarily stopping the web at the position of theapplicator device, the above apparatus is less suitable.

It is an object of the invention to provide a method of manufacturing anabsorbent article whereby the speed of the web can be varied whilekeeping the speed of the main upstream and downstream parts of the webconstant.

It is another object of the invention to periodically vary the speed ofa part of the web at high frequencies and high web speeds while keepingthe speed of the main-upstream and downstream parts of the web constant.

It is again another object of the invention to vary the speed of a partof the web exerting a low variation in tension on the web.

It is a further object of the invention to vary the speed of a part ofthe web without introducing significant frictional forces on the web.

It is a further object of the invention to vary the speed of a part ofthe web without causing movement of said part in a direction transverseto the direction of transport of the web.

SUMMARY OF THE INVENTION

The method according to the invention comprises running the web along anupstream and downstream guide roller, which rollers are translationallystationary relative to the frame and along an upstream and downstreamtransport roller that are periodically displaceable.

A first section of the intermediate trajectory of the web extendsbetween the upstream guide roller and the upstream transport roller.

A second, constant-length, section of the intermediate trajectoryextends between the upstream and downstream guide rollers or between theupstream and downstream transport rollers. When the second sectionextends between the upstream and the downstream guide rollers, thesection is stationary relative to the frame. When the second section ofthe intermediate trajectory extends between the upstream and thedownstream transport roller, the section is translated relative to theframe.

A third section of the intermediate trajectory extends between thedownstream guide roller and the downstream transport roller. The firstand third sections of the intermediate trajectory are parallel to thesecond section of the intermediate trajectory.

When the transport rollers are reciprocated in a direction parallel tothe second section of the intermediate trajectory, the lengths of thefirst and third sections of the intermediate trajectory are varied,while keeping constant the total length of the intermediate trajectoryand while keeping constant the length of the second section of theintermediate trajectory.

The transport rollers are rotated such that the strain exerted on theweb in running the web past the transport rollers is not substantiallylarger than the strain exerted on the web by the inertia forces actingon the web.

Because of the constant length of the intermediate trajectory of theweb, the time it takes for a part of the web to travel along the lengthof the intermediate trajectory is constant and is independent of thelocation of the intermediate trajectory relative to the stationaryframe. Hence, the movement of those parts of the web that are locatedalong the upstream and downstream trajectories, is not affected by thedirection and the speed of the displacement of the intermediatetrajectory relative to the frame.

Therefore, by moving the intermediate trajectory of the web relative tothe stationary frame, the speed at which the web travels along theintermediate trajectory can be adapted such that for those parts of theweb that are located along the intermediate trajectory, the velocityrelative to the stationary frame is increased, reduced, or reversed.

As the transport rollers are cyclically moved relative to the frame, therate at which the web travels along the transport rollers varies aroundthe constant speed of transport of the web along the upstream and thedownstream trajectories. The amplitude of the cyclical velocity of theweb along the transport rollers equals the amplitude of the velocitywith which the transport rollers are reciprocated relative to the frame.Hence, by driving the transport rollers in synchronism with thedisplacement of the transport rollers, the acceleration and decelerationforces for modulating the speed of the transport rollers are passed tothe transport rollers by the drive means, instead of by the web. Thisallows relatively weak webs to be accelerated and decelerated by themethod according to the invention, a low strain being exerted on thewebs.

Relative to the stationary frame, the second section of the intermediatetrajectory can be stationary or can be translationally displaced.

When the second section of the intermediate trajectory extends between astationary upstream and a stationary downstream guide roller, the secondsection is stationary relative to the frame. An embodiment of the methodaccording to the invention, in which the second section of theintermediate trajectory is stationary, is arrived at by passing the webalong a path formed by an upper and a lower S-shaped loop. The bottomleg of the upper S-shaped loop is connected to the top leg of the lowerS-shaped loop. The first and third sections of the intermediatetrajectory correspond to the middle legs of the upper S-shaped loop andthe lower S-shaped loop respectively. The second section of theintermediate trajectory corresponds to the combined bottom leg of theupper S-shaped loop and the top leg of the lower S-shaped loop.

Two stationary guide rollers are located in the bottom half of the upperS-shaped loop and the top half of the lower S-shaped loop respectively.Two transport rollers are located in the top half of the upper S-shapedloop and the bottom half of the lower S-shaped loop respectively.

The incoming web is fed from the upstream trajectory, past the upstreamtransport roller to the upstream guide roller, continues past thedownstream guide roller to the downstream transport roller to thedownstream trajectory. By moving the transport rollers in the transportdirection of the incoming web at half the web speed, the incoming web isstored along the increased length of the top half of the upper S-shapedloop. The parts of the web that are located along the second section ofthe intermediate trajectory are then stationary relative to the frame.

By moving the transport rollers against the transport direction, thelength of web that was stored along the top half of the upper S-shapedloop is accelerated along the second section of the intermediatetrajectory, and is fed to the downstream trajectory of the web.

The first embodiment in which the second section of the intermediatetrajectory is periodically translated relative to the stationary framecan be arrived at by interchanging the positions of the transportrollers and the guide rollers in the previously described upper andlower S-shaped loop configuration. In this case, when the transportrollers are moved against the direction of transport of the incoming webat half the web speed, part of the incoming web is stored along thefirst trajectory, and part of the incoming web travels along the secondtrajectory at half the web speed, in the transport direction of the web.As the second section of the intermediate trajectory itself movesagainst the transport direction of the web, the position of the webrelative to the frame is again stationary.

A preferred embodiment of the method according to the invention, inwhich the second section of the intermediate trajectory is translated,comprises feeding the web in a configuration which is formed by a firstS-shape loop and a reverse S-shaped loop, which are connected in aback-to-back manner via their lower legs. The transport rollers arelocated in the lower halves of each S-shaped loop and the guide rollersare located in the top halves of each S-shaped loop.

The first and third sections of the intermediate trajectory correspondto the middle legs of both S-shaped loops and the second section of theintermediate trajectory corresponds to the combined lower legs of theS-shaped loops. The advantage of the above configuration, is that theupstream and the downstream trajectories of the web are located in thesame plane and that the centre line of the downstream trajectory is notdisplaced.

It is essential in the method according to the invention, that the firstand third sections of the intermediate trajectory are parallel to thethird section. The term "parallel" is intended to include curvilineartrajectories, the perpendicular distance between which is constant. Forinstance, all sections of the intermediate trajectory may be locatedalong straight lines, or the first and third sections of theintermediate trajectory may be located on segments of a first circle,the second section being located on a segment of a second circle, whichis concentric with the first circle. Only when the parallel relationshipbetween the first and third sections on the one hand, and the secondsection on the other hand, is maintained, will the total length of theintermediate trajectory be constant, independent of the position of thetransport rollers.

By periodically varying the speed of the transport rollers with anamplitude of half the speed of transport of the web, the speed of theweb relative to the frame periodically becomes zero, in threeperpendicular directions. This allows operations to be performed on theweb by applicator apparatus interacting with the web, the applicatorapparatus being positionally stationary relative to the frame.

As the maximum speed of the transport rollers can be limited to half theweb speed or less, in order to temporarily stop the web, the method canbe applied at high frequencies and high web speeds, while maintainingthe accelerations of the transport rollers relatively small.

In the method according to the invention, the centre lines of theupstream and the downstream parts of the web are not displaced in adirection parallel to the plane of the web. This allows the method to beused in production lines through which the web passes in a straightline, without having to realign the downstream part of the productionline, or the use of an extra deflection member to realign the centreliner of the downstream part of the web.

In an embodiment of the method according to the invention, also theguide rollers are rotated to reduce the strain exerted on the web by theguide rollers. The guide rollers can be driven at a constant speed, suchthat their circumferential velocity corresponds to the transportvelocity, V₀, of the web.

Because of the low strain exerted on the web by the transport rollersand the guide rollers, the web can be passed along the rollers at thehigh speeds, such as 5 m/s, and higher which are customary in disposablediaper manufacture.

In one embodiment of the method and apparatus according to theinvention, the guide rollers and the transport rollers are driven by adrive member which is coupled with the guide rollers and the transportrollers to form a closed loop, a part of which extends parallel to theintermediate trajectory, the drive member being driven at a constantspeed, which equals the speed of transport of the web.

Running a drive belt in parallel with the web, allows the guide rollersto be driven at a constant speed and the transport rollers to be drivenat a cyclically varying speed, by a single constant speed drive motor.The torque for driving the rollers is derived from the drive belt,rather than from the web, so that the relatively weak webs used indiaper manufacture can be run through the apparatus.

A further embodiment of the apparatus in accordance with the inventioncomprises rotation-balancing means which are rotationally coupled to thetransport rollers, the rotation-balancing means being comprised of a twodiscs which are rotationally mounted on the frame. Each disc is linkedto a pair of pulleys by a belt. The pulleys are connected to the sled onwhich the transport rollers are mounted, one pulley of each pair beingdriven by a respective transport member. A belt forms a closed looparound each disc and the respective pulleys. When the sled isreciprocated, the pulleys are translated within each closed loop of thebalancing means, so that the speed of rotation of each disc differs inphase from the speed of rotation of the transport members by 180°, i.e.the speed of the discs increases when the speed of the transport membersdecreases and vice versa. This allows the combined transport members andbalancing means to be run at constant torque by a drive motor drivingthe rotation balancing means and the transport members. Coupling of thetransport members to balancing discs allows high speed movement of thesled, for instance at a rate of 550 rpm and a corresponding high rate ofvariation of the speed of the transport rollers.

Another embodiment of an apparatus for making an absorbent articleaccording to the invention comprises translation-balancing means tomaintain a generally constant position of the centre of mass of thecombined balancing means, the transport rollers and the sled.

The two transport rollers are connected to a sled which is mounted onthe frame so as to be movable relative to the frame, generally parallelto the direction of transport. Preferably the sled is suspended from theframe by a suspension means comprising two vertical arms, a lower end ofeach arm being connected to a respective end of the sled, each verticalarm being at its upper end hingably connected to the frame.

Allowing the sled to swing on the frame obviates the need for linearbearings, and allows for reciprocation at relatively high frequenciesusing a simple drive mechanism such as a reciprocating cantilever.Preferably the amplitude of reciprocation of the sled can easily beadjusted by varying the distance between the pivot point of thecantilever at the point of connection of the cantilever to the sled. Tothe cantilever, a displacement balancing means is connected in the formof for instance a rotary mass balance or a planetary gear box. Balancingboth the translational movement of the sled and the rotary movement ofthe transport rollers, allows the apparatus to be run at highfrequencies (above 10 Hz) which is required in efficient disposablediaper manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the method and apparatus according to the invention willbe described in detail with reference to the accompanying drawings. Inthe drawings:

FIG. 1 shows a side elevational view of a production line for themanufacture of an absorbent product,

FIG. 2 shows a schematic side elevational view of an embodiment of theapparatus according to the invention,

FIGS. 3a, 3b and 4 schematically show embodiments of an apparatusaccording to the invention, wherein the intermediate trajectory istranslated,

FIG. 5 shows the speed of the sled, transport rollers and web in theapparatus of FIGS. 3a and 4,

FIGS. 6 and 7 schematically show embodiments of the apparatus accordingto the invention wherein the intermediate trajectory is translationallystationary,

FIG. 8 shows the speed of the sled, transport rollers and web in theapparatus of FIGS. 6 and 7,

FIG. 9 shows a schematic perspective view of the apparatus according tothe invention,

FIG. 10 shows a schematic perspective view of the translation-balancingmeans and the rotation-balancing means,

FIG. 11a and 11b schematically show the functioning of therotation-balancing means

FIG. 12 shows a side-elevational view of the translation-balancingmeans,

FIGS. 13a-13d schematically show the functioning of thetranslation-balancing means,

FIG. 14 schematically shows the funcitoning of the suspension meanscarrying the sled,

FIG. 15 shows a perspective view of the drive mechanism for rotating thedrive rollers and the guide rollers,

FIG. 16 shows a partially cut-away plan view of an absorbent article,

FIG. 17 shows a cross-sectional view of the absorbent article of FIG. 16along the line 2--2,

FIG. 18 shows a schematic frontal view of a diaper manufacturing linecomprising the apparatus according to the invention,

FIGS. 19a and 19b show schematic side views of the applicator means forimparting regions of extensibility to the web,

FIG. 20 shows a plan view of a diaper provided with regions ofextensibility using the apparatus of FIGS. 19a and 19b, and

FIG. 21 shows a schematic side-view of applicator means for depositingabsorbent gelling material in an absorbent article.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows side-elevational view of a continuous process for making anabsorbent product 144. A continuous web 1 is assembled from an absorbentpad element, or core 120, which is encased between a liquid-pervioustopsheet 121 and a liquid impervious backsheet 123. The absorbent cores120 are fed into the nip between a pair of laminating rolls 125,126 atregularly spaced intervals by means of an infeed conveyor 127. In apreferred embodiment, the cores 120 are comprised of airfelt, within acellulosic tissue envelope, to provide integrity to the core in use. Thebacksheet 123 is coated on its inner surface with beads or spirals ofadhesive 128, for affixing the backsheet to the core 120. Continuousbands of elastic 130 are fed from metering rolls 131, 132 and 133 past aglue nozzle 135. The S-wrap arrangement of the rolls 131, 132 and 133minimises deformation of the elastic band 130 and allows for accuratecontrol of the speed of the elastic. The elastic bands are fed into thedirection of transport, F, at a lower speed than the cores 120, thebacksheet 123 and the topsheet 121, so that the elastic bands 130 arestretched. After passing through the combining nip, the web passes ontoa perforated vacuum conveyor belt 137. A vacuum suction box 139 drawsthe web against the conveyor belt 137, to maintain a uniform tension inthe elasticised web 1. Excess backsheet 123 and topsheet 121 are removedby rotating trim knife 141 and anvil 143, for instance to form sidenotches in a diaper. The web 1 is subsequently passed at a constantspeed of transport to the infeed side 4 of the apparatus 2 according tothe invention, for periodically changing the speed of web. In theapparatus 2, the web 1 can be slowed down, or stopped and is contactedby applicator means 38, or 38'. The applicator means can comprise meansfor providing a strip of material, such an elastic strand or strip, awaist cap or a strip of reinforcement material in the cross-machinedirection, i.e., the direction which is perpendicular to the directionof transport F and which is perpendicular to the plane of the drawing.The applicator means 38,38' can be located on the side of the topsheet121 or on the side of the backsheet 123. The latter is useful if areinforcement strip is attached to the backsheet, which reinforcementstrip serves as a landing member for refastenable adhesive tapefasteners. A reinforcement strip of this kind has for instance beendescribed in European patent EP-B- 0 286 030.

The web 1 leaves the outfeed side 6 of the apparatus 2 at the constantweb speed. The speed of the web portions located upstream and downstreamfrom the apparatus 2 along upstream trajectory 3 and downstreamtrajectory 5 is not affected by the change in speed of those parts ofthe web 1 that are passing through the apparatus 2.

FIG. 2 shows the apparatus 2 for changing the speed of a flexible web 1of relatively low tear strength. With flexible, it is meant that the web1 can be transported along a curvilinear trajectory and will adapt itsshape so as to conform to the trajectory. The web 1 is formed offlexible material, such as paper, airfelt, plastic etc. and can becomprised of the core 120, the topsheet 121, the backsheet 123 or anycombination thereof.

The web 1 is transported along upstream trajectory 3 with a constantvelocity of transport, V₀, in the machine direction F. The upstreamtrajectory 3 is formed by the length of the web 1 which extends to theright of the first guide roller 9 in FIG. 2, and which is moving towardsthe infeed side 4 of the apparatus. After passing through the apparatus,the web 1 exits at the outfeed side 6 and is transported at constantvelocity V₀ along the downstream trajectory 5, which extends to the leftof the guide roller 11. The upstream and the downstream trajectoriesneed not correspond to the machine direction, and can be formed bystraight-line or curvilinear paths.

The guide rollers 9 and 11 are rotationally connected to the frame 35.The guide rollers 9,11 have a fixed position. The web 1 is looped aroundan upstream and a downstream transport roller 13,15 which are mounted ona sled 41. The sled 41 is cyclically translated along the frame 35,generally parallel to the machine direction F, by drive motor 36.

An intermediate trajectory 7a, 7b, 7c of the web 1 is located betweenthe upstream guide roller 9 and the downstream guide roller 11, andcomprises a first section 7a and a third section 7c, of variable length,located between the upstream guide roller 9 and the upstream transportroller 13 and the downstream transport roller 15 and the downstreamguide roller 11 respectively. The second section 7c of the intermediatetrajectory 7 is located between the transport rollers 13 and 15 and isof constant length.

Because of the symmetry of the intermediate trajectory 7a, 7b, 7c, theincrease in length of the first section 7a, upon displacement of thesled 41 opposite to the machine direction F and away from theequilibrium position 39, is compensated by an equal decrease in lengthof the third section 7c, and vice versa. As the length of the secondsection 7b is constant, the whole intermediate trajectory 7 is ofconstant length. Hence the time for the web 1 to travel past theintermediate trajectory 7a, 7b, 7c is independent of the position of thesled 41 with respect to the frame 35.

When the part of the web that is located along the second section 7b ofthe intermediate trajectory 7a, 7b, 7c, is stationary relative to theframe 35, the web 1 is contacted by applicator means 29, 29', 38, 38'which positionally stationary with respect to the frame 35. Theapplicator means comprise a pair of vertically displaceable tampers 29,29' which press the web 1 against the lower parts 38, 38' of theapplicator means. After the applicator means have interacted with theweb 1, the web is accelerated along the section 7b of the intermediatetrajectory towards the outfeed side 6 of the apparatus 2, and issupplied to the downstream trajectory 5 with web speed V₀.

The guide rollers 9,11 and the transport rollers 13,15 are driven by adrive member in the form of a closed loop 50 and pulleys 52,53 and 54.The loop 50 is partly parallel to the intermediate trajectory 7a, 7b,7c. The loop 50 is driven at a constant speed which is equal to thespeed of transport, V₀, of the web 1 by a single drive motor 51. Bydriving the guide rollers 9,11 and the transport rollers 13, 15, thestrain exerted on the web 1 is minimized and can be limited to theacceleration forces, which are acting to change the speed of the web.

FIGS. 3a,3b and 4 illustrate embodiments in which the intermediatetrajectory 7a, 7b, 7c is translated with respect to the stationary frame35. In the embodiment of FIG. 3a, the guide rollers 9,11 and thetransport rollers 13,15 are arranged in a double S-shaped loop in whicha left-hand, reverse S-shaped loop comprising the downstream guideroller 11 and the downstream transport roller 15, is connected via itsbottom leg to a right-hand S-shaped loop comprising the upstreamtransport roller 13 and the upstream guide roller 9.

In the embodiment of FIG. 3b, the sled 41 comprises two pairs oftransport rollers 13,13' and 15,15'. The intermediate trajectory 7comprises the part of the web 1 which is located between upstream guideroller 9' and downstream guide roller 11'. The web 1 is stationaryrelative to the frame 35 along section 7b of the intermediate trajectory7 when the sled 41 moves against the direction of transport, F, with avelocity of V₀ /4. The addition of n pairs of guide rollers to the frame35 and n pairs of transport rollers to the sled 41, allows the speed ofthe sled 41 to be reduced to V₀ /2n to stop the motion of the web 1along section 7b. Hence, the web 1 can be run at a relatively highspeed, while maintaining the speed of the sled 41 relatively low,although the construction of the sled becomes more complicated uponaddition of extra pairs of transport rollers.

In the embodiment of FIG. 4, the transport rollers and the guide rollersare configured in an upper and lower S-shaped loop. Upon displacement ofthe sled 41 in the upstream direction (opposite to the direction oftransport, F), parallel to the sections 7a,7b and 7c, the first section7a of intermediate trajectory is elongated. Generally the direction ofdisplacement of the sled 41 will correspond to the direction oftransport, F, in which the web 1 is transported towards the input side 4of the apparatus. However, as is indicated in FIG. 3a, the web 1 can betransported towards the input side 4 and away from the output side 6 atany desired angle, the direction F' being for instance vertical asindicated by the broken lines in FIG. 3a.

A part of the incoming web is stored along the increased length ofsection 7a. The parts of the incoming web that cannot be accommodatedalong the increased length of section 7a, slip past the upstreamtransport roller 13, via the downstream transport roller 15 and guideroller 11 to the downstream trajectory 5. At the downstream side, thesection 7c is shortened by the same amount by which section 7a isincreased. The length of web located along the decreased length ofsection 7c is also passed to the downstream trajectory 5.

When the sled 41 moves against the direction of transport F at a speedV_(T), the increase in length of the section 7a in a predetermined timeinterval, is proportional to V_(T) m. In the predetermined timeinterval, the length of incoming web 1 is proportional to V₀ m, whereinV₀ is the constant velocity of transport of the web 1 along the upstreamand downstream trajectories 3, 5. The rate at which the web slips pastthe upstream transport roller 13 in the direction of transport, is equalto V₀ -V_(T), which is the relative speed of the web 1 with respect tothe sled 41 and the transport rollers 13,15. As the sled 41 moves at aspeed V_(T) against the direction of transport, the relative velocity ofthe web,V_(W), relative to the stationary frame 35 is equal to V₀-2V_(T).

At the downstream side, the decrease in length of section 7c isproportional to V_(T) m. This length of web is supplied to thedownstream trajectory 5. Also supplied to the downstream trajectory 5 isthe length of web, slipping past the transport rollers, 13, 15 which isproportional to V₀ -V_(T) m, so that the total length supplied in thepre-determined time interval to the downstream trajectory 5 isproportional to V₀ m. Hence, the velocity of the web 1 along thedownstream trajectory 5 remains unaltered, and is independent of thespeed V_(T) of the sled 41.

It follows that if the sled 41 moves against the transport direction F,at a speed equal to half the speed of transport of the web 1 (V_(T) =V₀/2), the web 1 travels along the second section 7b of the intermediatetrajectory 7 at the same speed at which the section 7b is moved alongthe frame 35.

Hence, the net displacement of the web along the second section 7b,relative to the stationary frame 35, is zero. If the sled 41 movesagainst the transport direction at a speed V_(T) which is slower thanhalf the speed of transport, V_(o) /2, the web 1 is slowed down relativeto the frame 35, along the second section 7b of the intermediatetrajectory 7a, 7b, 7c. If the sled 41 moves at a speed, V_(T), fasterthan half the speed of transport, V_(o) /2, the speed of the web alongthe second section 7b of the intermediate trajectory 7 is reversedrelative to the stationary frame 35, and is directed against thetransport direction. F.

Upon reversal of the speed of the sled 41 in the direction of transportF, the length of section 7a is in a pre-determined time intervalshortened by a length which is proportional to V_(T) m. This length ofweb, as well as a length proportional to V₀ m of incoming web, travelspast section 7b of the intermediate trajectory 7. As section 7b itselftravels at V_(T) m/s past the frame 35, the speed of the web 1, VW,relative to the stationary frame 35 equals V₀ +2V_(T) in the directionof transport, F. At the downstream side, the section 7c has increased bya length which is proportional to V_(T) m.in the pre-determined timeinterval. This length of web, as well as a length proportional to V₀ mthat is to be transported to the downstream trajectory 5, needs to besupplied past downstream transport roller 15. Hence the speed with whichthe web needs to be supplied past the downstream transport roller 15,corresponds to the speed of the web along section 7b (V₀ +V_(T) m/s).

In FIG. 5 the speed of the web 1 relative to the stationary frame,V_(W),along the second section 7b of the intermediate trajectory 7, has beengraphically indicated for a cyclical speed of the sled 41, V_(T), withan amplitude V₀ /2, equal to half the velocity of transport. The speedof the web relative to the second section 7b of the intermediatetrajectory 7 has been indicated as V_(R). V_(R) corresponds to thecircumferential velocity of the transport rollers 13 and 15. It can beseen that the speed of the web V_(W) along section 7b, relative to thestationary frame, is in phase with the speed V_(T) of the sled 41 andvaries around the constant speed of transport V₀ between 0 and twice theconstant speed of transport. The circumferential speed of the transportrollers is also in phase with the speed of the sled 41 and varies aroundV₀ between V₀ /2 and 3V₀ /2.

FIGS. 6 and 7 show embodiments of the apparatus 2 in which the secondsection 7b of the intermediate trajectory 7 is translationallystationary relative to the frame 35.

Moving the sled 41 in FIG. 6 in the transport direction F at half thespeed of transport, causes the upstream trajectory 3 and the section 7ato be increased in length. The incoming web 1 is stored along thisincreased length, so that the speed of the web along section 7b isstationary. At the same time, the downstream trajectory 5 and thesection 7c are shortened, and the parts of the web that were locatedalong these sections are supplied to the downstream trajectory 5.

Reversal of the movement of the sled, causes the web that was locatedalong the increased lengths of the upstream trajectory 3 and section 7a,to be accelerated along section 7b to the downstream side 5.

The embodiment of the method and apparatus as shown in FIG. 7 worksaccording to the same principles as the embodiment of FIG. 6. In FIG. 7,the sections 7a and 7c of the intermediate trajectory 7, are located ona first cylindrical surface along transport roller extension means 55,57. The second section 7b of the intermediate trajectory 7 is located onthe surface of a drum 59. Upon moving of the sled 41 concentrically withthe axis 61 of the drum 59, in an anticlockwise direction, the lengthsof the section 7a and the upstream part of section 7b are increased. Thelengths of the downstream side of section 7b and the third section 7care decreased in length such that the combined length of sections 7a and7c as well as the length of section 7b is constant.

When the transport rollers 13,15 are moved with the sled 41 in apredetermined time interval along a section of the circumference of thedrum 59 which is proportional to half the velocity of transport, abouthalf the incoming web is stored along the increased length of section 7aand about half the incoming web is stored along the increased upstreampart of section 7b. The velocity of the web along section 7b, relativeto the frame is constant.

In FIG. 8, the web speed, V_(W) along section 7b and the circumferentialspeed V_(R) of the transport rollers 13, and 15 are given for cyclicdisplacement of the sled 41 along a trajectory concentric with the axis61 of the drum 59, with a velocity V_(T) having an amplitude of half thespeed of transport of the web. The circumferential speed of thetransport rollers is indicated as V_(R). When the drum 59 isrotationally connected to the frame, the circumferential speed of thedrum will correspond to the web speed,V_(W). The velocity and phaserelationships of FIG. 8 also apply to the embodiment of FIG. 6.

FIGS. 9 and 10 show a perspective view of the embodiment of theapparatus in which the guide rollers 9, 11 and the transport rollers 13,15 are rotationally mounted on the sled 41. The sled 41 is suspendedfrom the frame 35, which has been schematically indicated in thesefigures, via suspension means 79,79'. The sled 41 is driven by acantilever 71, which is pivotably connected to the sled in a drive point73. The transport rollers 13,15 are connected to rotation-balancingmeans 63,63' which allow the transport rollers to be driven at aconstant torque. In the embodiment of FIG. 9, the rotation-balancingmeans drive a rotating balancing mass 62 via a closed loop member suchas belt or chain 64. The rotation- balancing means 63,63' rotate withthe same rotational velocity as the transport rollers to which they areconnected, and are simultaneously translated within the closed loopmember 64. As a consequence the balancing mass 62 is rotated insynchronism with the transport rollers but in the opposite direction tothe direction of rotation of the transport rollers. Hence the resultanttorque of the balancing mass 62 and the transport rollers 13,15 isconstant.

In a preferred embodiment of the invention, the rotation balancing means63,63' each comprises a disc 65, 65' which is rotatably connected to theframe 35. This is shown in FIG. 10. For each disc 65, 65' two pulleys67,69 and 67 and 69' are mounted on the sled 41. A belt 70,70' is loopedaround the balancing diso's 65, 65' and the pulleys 67, 69, 67', 69'.The pulleys 69,69' are each coupled to the axes 25,27 of the transportrollers, 13,15. The circumferential speed of the pulleys 69,69' is equalto V_(R).r/R wherein r is the radius of the pulleys 69,69' and R is theradius of the transport rollers 13,15.

The functioning of the balancing means 63,63' as shown in FIG. 10 hasbeen schematically indicated in FIGS. 11a and 11b. In FIGS. 11a and 11b,the position of the sled 41, has been indicated at its equilibriumposition 39 in solid lines and at a position close thereto, in brokenlines.

When the sled 41 is furthest from its equilibrium position 39 (aposition which has not been indicated in FIGS. 11a and 11b),the sled 41,and with it the pulleys 67,69, are translationally stationary. Thestationary positions of the sled 41 for the embodiments of FIGS. 3a, 3band 4, can be found in FIG. 5 at positions 0, T/2 and T of the x-axis.For a stationary sled 41, the belt 70 is driven by pulley 69 such thatthe circumferential speed of the disc 65 in this case is equal to thecircumferential speed of the pulley 69. When the speed of the sled 41,V_(T), is zero, it can be seen from FIG. 5 that the circumferentialspeed of the transport rollers, V_(R), is equal to the speed oftransport, V₀. For the case in which the radii of the pulleys 69, 69'are equal to the radii of the transport rollers 13,15, thecircumferential speed of the disc 65 equals V₀.

When the sled 41 is close to its equilibrium position 39, and is movedin the direction of transport, F, from the position indicated by thebroken line in FIG. 11a, to the position indicated by the solid line inFIG. 11a, the speed of the sled approximately equals V₀ /2. Thissituation can be found around time T/4 on the x-axis of FIG. 5. Whenpulleys 67 and 69 are in a pre-determined time interval displaced by adistance proportional to V₀ /2, a length of belt 70 proportional to V₀(the broken-line part at the right-hand side in FIG. 11a) needs to betransported past pulley 69 to pulley 67 to take up the slack. Norotation of the disc 65 is necessary. However, as can be seen from FIG.5, the rotational speed of the transport rollers and the pulleys thatare driven by the transport rollers, equals 3V₀ /2. Therefore, inaddition to the length V₀ of belt 70 that is moved past the pulleys 67and 69 upon translation of the pulleys, an additional length V₀ /2 ofbelt 70 needs to be supplied to pulley 69 by rotation of the belt 70past the disc 65. Hence the rotational speed of the disc 65 equals V₀/2.

When the sled 41 is close to its equilibrium position, and is movedagainst the direction of transport F, the speed of the sled again aboutequals V₀ /2. This situation is found around time 3T/4 on the x-axis ofFIG. 5, and is illustrated in FIG. 11b. Considering again a displacementof the pulleys 69 and 67 proportional to V₀ /2 in a pre-determined timeinterval, it can be seen that a length of belt 70, proportional to V₀needs to be taken up by rotation of disc 65. From FIG. 5 it can be seenthat the speed of the pulley 69, which is driven by the transport roller15, equals V₀ /2, so that in the given time interval an additionallength of belt 70, proportional to V₀ /2, is accumulated at the upstreamside of pulley 67. Therefore, in addition to the length proportional toV₀ that is to be passed from pulley 67, via the disc 65, to pulley 69,the pulley 67 supplies a length of belt 70 to disc 65 which isproportional to V₀ /2. Hence the speed of rotation of the disc 65 isproportional to 3V₀ /2.

As appears from the foregoing discussion, the rotation of the disc 65varies cyclically around the average speed, V₀, with a amplitude of V₀/2 and has a fixed 180° phase difference with the speed of rotation ofthe transport rollers 13,15. Only when the radii of the pulleys 67,69are equal in length to the radii of the transport rollers 13,15 will theamplitudes of the circumferential speed of the disc 65 be equal to thespeed of the transport rollers, V_(R). By adapting the mass distributionof the discs 65 to the moment of inertia of the transport rollers, theoverall variations in torque of the combined transport rollers 13,15 andthe discs 65, 65' with respect to an axis of the drive motor 51, can beminimized. Hence the drive motor 51 will not be adversely affected bythe high -frequency changes in rotational velocity of the transportrollers.

FIG. 12 shows a side-elevational view of the sled-balancing means 77,which is formed by a rotating mass balance that comprises two rotatingbalancing masses 80,81. The sled balancing means 77 comprises a housing87 having an inner circular track 85. The housing 87 is attached to theframe 35, and is stationary with respect to the frame. The cantilever 71is at its upper end connected to the balancing masses 80 and 81.

Rotating mass 80 compensates the inertia forces that are exerted on thecantilever 71 by the sled 41, such that the sled, the cantilever and thebalancing means can in combination be driven at a constant force. Thesled 41 performs a horizontal periodic motion, and is accelerated anddecelerated by the cantilever 71. The sled 41 exerts a periodic force onthe cantilever 71 that is proportional to the acceleration and that islargest when the speed of the sled is 0. The horizontal component of theforce exerted on the cantilever 71 by the rotating mass 80 is alsoperiodic and has the same frequency as the frequency of reciprocation ofthe sled 41, is equal in magnitude to the force exerted by the sled andis directed in the opposite direction. The mass 80 is driven, forinstance by a drive shaft 84, at a constant rotational speed. Thevertical component of the force exerted by the mass 80 on the housing87, is compensated by the mass 81, that travels up and down alongstraight-line path A-C.

The mass 81 is mounted on a disc 83, having a diameter equal to half thediameter of the circular track 85. The disc 83 is rotationally mountedinside the housing 87 and travels along the circular track 85. The disc83 may be formed by a pinion, the circular circumference 85 beingprovided with meshing gear teeth. The position of the balancing mass 81and the disc 85 at position B of the circular track 85, have beenindicated in FIG. 11 in broken lines. Further rotation of the disc 85 toposition C of the circular track 85, will move the centre of mass MBalong the line AC from the centre of the circular track 85 to point C.Further rotation of the disc 83 via position D, back to A, moves thecentre of mass MB back along line AC to position A.

In FIGS. 13a-13d it is schematically illustrated how the mass balancingsystem 77 interacts with the sled 41. The housing 87 comprising thecircular track 85 is connected to the frame 35 and is stationary withrespect thereto. A drive shaft 84, which extends perpendicular to theplane of the drawing and which passes through the center of the circulartrack 85, rotates the mass 80 at a constant rotational speed. The disc83 is at its center rotatably connected to the mass 80 such that uponrotation of the mass 80, the disc 83 is rotated along the track 85.

Upon rotation of the disc 83 along the track 85, the points of thecircumference of disc 83 that are located in positions corresponding topoint A and to the center of the track 85 in FIG. 13a, move alongstraight-line paths, that are diametrically located with respect to thecircular track 85.

The cantilever 71 is connected to a linkage 88 which is hingeablyconnected to the circumference of the disc 83 in a point J which inFIGS. 13a and 13c coincides with the center of circular track 85. Thedrive shaft 84 drives the mass 80 and the disc 83 at a constantrotational speed. As shown in FIGS. 13a and 13c, the sled 41, which hasbeen schematically indicated, is in its equilibrium position. Since thesled 41 is suspended from the frame 35 via suspension means 79, 79',which are preferably formed by a an Evans linkage (which has not beenshown in FIGS. 13a-13d), the sled only exerts horizontal inertia forceson point J. As the acceleration of the sled 41 is 0 in its equilibriumposition, no horizontal forces are exerted by the sled on point J inthis position. The vertical force exerted on the housing 87 by therotating mass 80, is in the equilibrium position compensated by theforce exerted by the mass 81, which is accelerated towards the center ofcircular track 85.

Upon rotation of the disc 83 in the direction of arrow Q, the point Jmoves along a straight-line path from the center of the track 85 topoint B, as shown in FIG. 13b. The balancing mass 81 moves from positionA to the center of track 85. When the cantilever 71 and the sled 41reach their maximum deflection and the sled is accelerating in thedirection of arrow Fs, the horizontal inertia force exerted by the sledon point J is at its largest and is directed opposite to the directionof arrow Fs. The horizontal component of the force exerted on thehousing 87 by rotating mass 80 is also at is maximum value and isdirected in the direction opposite to arrow Fb, and compensates theforce exerted on the point J by the sled 41.

The mass 81, which in FIGS. 13b and 13d has been indicated by the brokenlines, is located in the center of circular track 85, and moves in thisposition at maximum, constant speed. Hence, no inertia force is exertedby the mass 81 on the housing 87.

Upon further rotation of the disc 83, the mass 81 reaches point C,reverses its direction of straight-line movement, and travels back tothe center of track 85, as has been shown in FIG. 13c. The forces actingon the housing 87 and point J in FIGS. 13c and 13d are identical inmagnitude and opposite in direction to the forces that act in theposition of the sled 41 as shown in FIG. 13a and 13b respectively.

The weight of the balancing masses 80,81 and he distances of thebalancing masses from the drive shaft 84 will depend on the actualconfiguration of the sled 41 and the cantilever 71, and can on the basisof the above principles easily be determined. The principle of themass-balancing of the sled 41 is also applicable to constructions, inwhich the cantilever 71 is driven by other means than the rotating driveshaft 84.

The suspension means 79,79' as shown in FIGS. 9 and 10 comprise a Evanslinkage, the principle of which has been schematically indicated in FIG.14. In the Evans linkage, a vertical suspension arm 89 is suspended inrotation point 97. The sled 41 is suspended at the lower end 96 of thesuspension arm 89. Rotation of the vertical suspension arm 89 around therotation point 97, causes the lower end 96 of the arm 89 to follow acircular rotation path 101. In order to have the lower end of the arm 89move along a straight-line path 105, the centre of rotation 97' needs tobe displaced upon rotation of the arm 89. The suspension arm 89 isthereto connected to a rotation arm 86, which in FIG. 14, for thevertical position of the suspension arm 89, is located behind thesuspension arm. The rotation arm 86 is rotatable around rotation point95, and positions 91 and 94 of the rotation arm 86 have been indicated.The length of the rotation arm 86 is of generally half the length ofsuspension arm 89.

When the rotation arm 86 is moved to position 91, the lower end of thesuspension arm 89 can be located on circular path 106 which is indicatedby a broken line. The lower end of the suspension arm 89 will be locatedon straight-line path 105 for position 91 of the rotation arm 86 whenthe upper end of the suspension arm 89 is moved vertically downwards.The upper end of the suspension arm 89 is in a hinging point 108connected to a transverse arm 93. As the transverse arm 93 is ofrelatively large radius, and the angle of rotation of the arm 93 isrelatively small, the path of the hinging point 108, which is part ofthe circular path 103, approximately corresponds to the verticaldisplacement of the upper end of the arm 89.

Via the suspension means 79, the sled 41 can be reciprocated along asubstantially straight line path 105 without the need for linearbearings. This allows the sled to be reciprocated at a high speedwithout intensive maintenance requirements to the bearings of thesuspension means.

FIG. 15 shows a perspective view of the drive mechanism for rotating theguide rollers 9,11 and the transport rollers 13,15 in accordance withthe speeds as shown in FIGS. 5 and 8. The drive member 50, which iscomprised of a belt, is passed around drive rollers 110, 112, 114 and116, in a path which is parallel to the web 1. The drive rollers 110 and114 are equal in diameter to the guide rollers 9 and 11, and rotate at aconstant velocity V₀ which corresponds to the velocity of the upstreamand the downstream parts of the web 1. The drive rollers 112 and 116 areequal in diameter to the transport rollers 13 and 15, and rotate with acyclic speed of amplitude V₀ /2 around the speed of transport V₀. Thebelt 50 is passed along pulleys 113 and 111 and forms a closed loop. Thepulley 113 is driven by a drive motor, 51, at a constant speed V₀. Dueto the reciprocation of the transport rollers 13,15, the belt 50 passesalong these rollers at the above cyclic speed. The belt 50 drives theguide rollers 9,11 at the constant speed V₀.

As used herein, the term "absorbent article" refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term "disposable" is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A"unitary" absorbent article refers to absorbent articles which areformed of separate parts united together to form a co-ordinated entityso that they do not require separate manipulative parts like a separateholder and liner. A preferred embodiment of an absorbent article of thepresent invention is the unitary disposable absorbent article, diaper144, shown in FIG. 16. As used herein, the term "diaper" refers to anabsorbent article generally worn by infants and incontinent persons thatis worn about the lower torso of the wearer. It should be understood,however, that the present invention is also applicable to otherabsorbent articles such as incontinent briefs, incontinentundergarments, diaper holders and liners, feminine hygiene garments, andthe like.

FIG. 16 is a plan view of the diaper 144 of the present invention in itsfiat-out, state (i.e., with elastic induced contraction pulled out) withportions of the structure being cut-away to more clearly show theconstruction of the diaper 144 and with the portion of the diaper 144which faces or contacts the wearer, the inner surface, oriented towardsthe viewer. As shown in FIG. 16, the diaper 144 preferably comprises aliquid pervious topsheet 145; a liquid impervious backsheet 146 joinedwith the topsheet 145; an absorbent core 147 positioned between thetopsheet and the backsheet; side panels 148; elasticized leg cuffs 153;an elastic waist feature 154 and a fastening system generally multiplydesignated as 149.

FIG. 16 shows a preferred embodiment of the diaper 144 in which thetopsheet 145 and the backsheet 146 have length and width dimensionsgenerally larger than those of the absorbent core 147. The topsheet 145and the backsheet 146 extend beyond the edges of the absorbent core 147to thereby form the periphery of the diaper 144. While the topsheet 145,the backsheet 146, and the absorbent core 147 may be assembled in avariety of well known configurations. Preferred diaper configurationsare described generally in U.S. Pat. No. 3,860,003 entitled"Contractable Side Portions for Disposable Diaper" which issued toKenneth B. Buell on Jan. 14, 1975; and U.S. patent application Ser. No.07/715,152, allowed, "Absorbent Article With Dynamic Elastic WaistFeature Having A Predisposed Resilient Flexural Hinge", Kenneth B. Buellet al. filed Jun. 13, 1991; each of which is incorporated herein byreference.

FIG. 17 is a cross-sectional view of the diaper 114 taken along sectionline 2--2 of FIG. 16.

The absorbent core 147 may be any absorbent means which is generallycompressible, conformable, non-irritating to the wearer's skin, andcapable of absorbing and retaining liquids such as urine and othercertain body exudates. The absorbent core 147 may be manufactured in awide variety of sizes and shapes (e.g., rectangular, hourglass,"T"-shaped, asymmetric, etc.) and from a wide variety ofliquid-absorbent materials commonly used in disposable diapers and otherabsorbent articles such as comminuted wood pulp which is generallyreferred to as airfelt. Examples of other suitable absorbent materialsinclude creped cellulose wadding; meltblown polymers including coform;chemically stiffened, modified or cross-linked cellulosic fibers; tissueincluding tissue wraps and tissue laminates; absorbent foams; absorbentsponges; superabsorbent polymers; absorbent gelling materials; or anyequivalent material or combinations of materials. The configuration andconstruction of the absorbent core may also be varied (e.g., theabsorbent core may have varying caliper zones, a hydrophilic gradient, asuperabsorbent gradient, or lower average density and lower averagebasis weight acquisition zones; or may comprise one or more layers orstructures). The total absorbent capacity of the absorbent core 147should, however, be compatible with the design loading and the intendeduse of the diaper 144. Further, the size and absorbent capacity of theabsorbent core 147 may be varied to accommodate wearers ranging frominfants through adults. Exemplary absorbent structures for use as theabsorbent core 147 are described in U.S. Pat. No. 4,610,678 entitled"High-Density Absorbent Structures"; U.S. Pat. No. 4,673,402 entitled"Absorbent Articles With Dual-Layered Cores" issued to Weisman et al. onJun. 16, 1987; U.S. Pat. No. 4,888,231 entitled "Absorbent Core Having ADusting Layer" issued to Weisman on Dec. 19, 1989; and U.S. Pat. No.4,834,735, entitled "High Density Absorbent Members Having Lower Densityand Lower Basis Weight Acquisition Zones", issued to Alemany et al. onMay 30, 1989. Each of these patents are incorporated herein byreference.

The backsheet 146 is positioned adjacent the garment surface of theabsorbent core 147 and is preferably joined thereto by attachment means(not shown) such as those well known in the art. For example, thebacksheet 146 may be secured to the absorbent core 147 by a uniformcontinuous layer of adhesive, a patterned layer of adhesive, or an arrayof separate lines, spirals, or spots of adhesive. Adhesives which havebeen found to be satisfactory are manufactured by H. B. Fuller Companyof St. Paul, Minn. and marketed as HL-1258. The attachment means willpreferably comprise an open pattern network of filaments of adhesive asis disclosed in U.S. Pat. No. 4,573,986 entitled "DisposableWaste-Containment Garment", which issued to Minetola et al. on Mar. 4,1986 more preferably several lines of adhesive filaments swirled into aspiral pattern such as is illustrated by the apparatus and methods shownin U.S. Pat. No. 3,911,173 issued to Sprague, Jr. On Oct. 7, 1975; U.S.Pat. No. 4,785,996 issued to Ziecker, et Al. on Nov. 22, 1978; and U.S.Pat. No. 4,842,666 issued to Werenicz on Jun. 27, 1989. Each of thesePatents are incorporated herein by reference. Alternatively, theattachment means may comprise heat bonds, pressure bonds, ultrasonicbonds, dynamic mechanical bonds, or any other suitable attachment meansor combinations of these attachment means as are known in the art.

The backsheet 146 is impervious to liquids (e.g., urine) and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term "flexible" refers to materials which are compliant and willreadily conform to the general shape and contours of the human body. Thebacksheet 146 prevents the exudates absorbed and contained in theabsorbent core 147 from wetting articles which contact the diaper 144such as and undergarments. The backsheet 146 may thus comprise a wovenor material, polymeric films such as thermoplastic films of polyethyleneor polypropylene or, or composite materials such as a film-coatednonwoven material. Preferably, the backsheet is a film having athickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils).Particularly preferred materials for the backsheet include RR8220 blownfilms and RR5475 east films as manufactured by Tredegar Industries, Inc.of Terre Haute, Ind. The backsheet 146 is preferably embossed and/ormatte finished to provide a more clothlike appearance. Further, thebacksheet 146 may permit vapors to escape from the absorbent core 147(i.e.breathable,) while still preventing exudates from passing throughthe backsheet 146.

The topsheet 145 is positioned adjacent the body surface of theabsorbent core and is preferably joined thereto and to the backsheet 146by attachment means (not shown) such as those well known in the art.Suitable attachment means are described with respect to joining thebacksheet to the absorbent core 147. As used herein, the term "joined"encompasses configurations whereby an element is directly secured to theother element by affixing the element directly to the other element, andconfigurations whereby the element is indirectly secured to the otherelement by affixing the element to intermediate member(s) which in turnare affixed to the other element. In a preferred embodiment of thepresent invention, the topsheet 145 and the backsheet 146 are joineddirectly to each other in the diaper periphery 60 and are indirectlyjoined together by directly joining them to the absorbent core by theattachment means (not shown).

The topsheet 145 is compliant, soft feeling, and non-irritating to thewearer's skin. Further, the topsheet 145 is liquid pervious permittingliquids (e.g., urine) to readily penetrate through its thickness. Asuitable topsheet may be manufactured from a wide range of materials,such as porous foams; reticulated foams; apertured plastic films; orwoven or nonwoven webs of natural fibers (e.g., wood or cotton fibers),synthetic fibers (e.g., polyester or polypropylene or fibers), or acombination of natural and synthetic fibers. Preferably, the topsheet145 is made of a hydrophobic material to isolate the wearer's skin fromliquids contained in the absorbent core 147. There are a number ofmanufacturing techniques which may be used to manufacture the topsheet145. For example, the topsheet 145 may be a nonwoven web of fibers,spunbonded, carded, wet-laid, meltblown, hydroentagled, combinations ofthe above, or the like. A preferred topsheet is carded and thermallybonded by means well known to those skilled in the fabrics art. Apreferred topsheet comprises a web of staple length polypropylene fiberssuch as is manufactured by Veratec, Inc., a Division of InternationalPaper Company, of Walpole, Mass. under the designation P-8.

The diaper 144 preferably further comprises elasticized leg cuffs 153for providing improved containment of liquids and other body exudates.Each elasticized leg cuff 153 may comprise several different embodimentsfor reducing the leakage of body exudates in the leg regions. (The legcuff can be and is sometimes also referred to as leg bands, side flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003 describes adisposable diaper which provides a contractible leg opening having aside flap and one or more elastic members to provide an elasticized legcuff (gasketing cuff). U.S. Pat. No. 4,909,803 entitled "DisposableAbsorbent Article Having Elasticized Flaps" issued to Aziz et al. onMar. 20, 1990, describes a disposable diaper having "stand-up"elasticized flaps (barrier cuffs) to improve the containment of the legregions. U.S. Pat. No. 4,695,278 entitled "Absorbent Article Having DualCuffs" issued to Lawson on Sep. 22, 1987, describes a disposable diaperhaving dual cuffs including a gasketing cuff and a barrier cuff.

The Diaper 144 preferably further comprises an elastic waist feature 154that provides improved fit and containment. The elastic waist feature154 is that portion or zone of the diaper 144 which is intended toexpand and contract to dynamically fit the wearer's waist. The elasticwaist feature 154 at least extends longitudinally outwardly from atleast one of the waist edges of the absorbent core 147 and generallyforms at least a portion of the end edge 155 of the diaper 144.Disposable diapers are generally constructed so as to have two elasticwaist features, one positioned in the first waist region and onepositioned in the second waist region, although diapers can beconstructed with a single elastic waist feature. The elastic waistfeature or any of its constituent elements can comprise a separateelement affixed to the diaper 144, as shown in FIG. 17. Pre-stretchedelastic spacing members 157, connected to an upper end of the waistfeatures 154, cause the waist features 154 to stand up above the planeof the topsheet 145.

The elastic waist 154 may be constructed. in a number of differentconfigurations including those described in U.S. Pat. No. 4,515,595issued to Kievit et al. on May 7, 1985 and the above referenced U.S.patent application Ser. No 07/715,152; each of these references beingincorporated herein by reference.

The diaper 144 also comprises a fastening system which forms a sideclosure which maintains the first waist region 150 and the second waistregion 152 in an overlapping configuration such that lateral tensionsare maintained around the circumference of the diaper to maintain thediaper on the wearer. Exemplary fastening systems are disclosed in U.S.Pat. No. 4,846,815 entitled "Disposable Diaper Having An ImprovedFastening Device" issued to Scripps on Jul. 11, 1989; U.S. Pat. No.4,894,060 entitled "Disposable Diaper With Improved Hook FastenerPortion" issued to Nestegard on Jan. 16, 1990; U.S. Pat. No. 4,946,527entitled "Pressure-Sensitive Adhesive Fastener and Method of MakingSame" issued to Battrell on Aug. 7, 1990; U.S. Pat. No. 3,848,594entitled "Tape Fastening System for Disposable Diaper" issued to Buellon Nov. 19, 1974; U.S. Pat. No. B1 4,662,875 entitled "AbsorbentArticle" issued to Hirotsu et al. on May 5, 1987; and the hereinbeforereferenced U.S. patent application Ser. No. 07/715,152; each of which isincorporated herein by reference.

In a preferred embodiment, the diaper also comprises elasticized sidepanels 158 disposed in the first waist region 150. (As used herein, theterm "disposed" is used to mean that an element(s) of the diaper isformed (joined and positioned) in a particular place or position as aunitary structure with other elements of the diaper or as a separateelement joined to another element of the diaper. The elasticized sidepanels 158 provide an elastically extensible feature that provides amore comfortable and contouring fit by initially conformably fining thediaper to the wearer and sustaining this fit throughout the time of wearwell past when the diaper has been loaded with exudates since theelasticized side panels allow the sides of the diaper to expand andcontract. The elasticized side panels 158 further provide more effectiveapplication of the diaper 144 since even if the diaper pulls oneelasticized side panel farther than the other during application(asymmetrically), the diaper 144 will "self-adjust" during wear. Whilethe diaper 144 of the present invention preferably has the elasticizedside panels 158 disposed in the first waist region 150; alternatively,the diaper 144 may be provided with elasticized side panels 158 disposedin the second waist region 152 or in both the first waist region 150 andthe second waist region 152. While the elasticized side panels 158 maybe constructed in a number of configurations, examples of diapers withelasticized side panels positioned in the ears (ear flaps) of the diaperare disclosed in U.S. Pat. No. 4,857,067, entitled "Disposable DiaperHaving Shirred Ears" issued to Wood, et al. on Aug. 15, 1989; U.S. Pat.No. 4,381,781 issued to Sciaraffa, et al. on May 3, 1983; U.S. Pat. No.4,938,753 issued to Van Gompel, et al. on Jul. 3, 1990; and thehereinbefore referenced U.S. patent application Ser. No. 07/715,152;each of which are incorporated herein by reference.

FIG. 18 shows a frontal view of the apparatus 2 according to theinvention and the applicator means 38 for applying a pre-stretched stripof elastic material, for instancek, laminate elastic material 161 to theweb 1, such as for instance a waistband or a waistcap 154. The directionof transport of the web 1 is perpendicular to the plane of the drawing.The elastic material is 161 unwound from a roll by a metering elementcomprising two rolls 159, 160. Roll 159 is driven at slower speed thanroll 160, so that the strip of elastic material is pre-stretched. Theelastic material is fed along an automatic tracking system 162 tominimize cross-machine directional placement variations of the elasticmaterial at the metering point that is located at the infeed point ofthe rotating perforated conveyor belt 165. A glue coater 164intermittently coates the elastic material 161 with a continuous, orspiral-patterned layer of glue. The prestretched elastic material 161 istightly held on the perforated conveyor belt 165 by action of vacuumsuction box 166. The rotating conveyor belt 165 passes the elasticmaterial under a crush knife 167, and subsequently rotates the elasticmaterial in a parallel position to the web 1. The web 1 is stopped bythe apparatus 2, and the air cylinders 29,29', as shown in FIG. 2, pushthe web 1 against the elastic element 161. Each air cylinder comprises atamper foot. After a short dwell-time (a few milliseconds), the tamperfeet of the air cylinders 29, 29' are moved upwards and the web 1 isaccelerated in the direction of transport. Upon actuation of theair-cylinders 29,29', the vacuum acting on the prestretched elasticmaterial 161 is switched off by means of a mechanical switch, blockingthe access of the apertures in the conveyor 167 to the vacuum suctionbox 166. The movement of the transport rollers 13,15, the mechanicalvacuum switch of the vacuum suction box 166, the air cylinders 29,29'the glue coater 164 and the crush knife 167 are all synchronised tomaintain the proper phase relationship between the different movements.

FIG. 19a shows an embodiment in which the applicator means 38,38'comprise a pair of corrugated members 170, 171 having intermeshingteeth, for physically deforming the web 1. When the corrugated members170, 171 are clamped down on the web 1, the web is deformed alongparallel lines, corresponding to the corrugations which in this caseextend perpendicular to the plane of drawing. The web has increasedextensibility in the direction perpendicular to the lines of thedeformations, the web 1 being after contacting with the corrugatedmembers 170, 171 elongatable in a harmonica-like fashion. By stoppingthe web 1, relative to the corrugated members 170, 171, a complexpattern of deformation can be applied to the web which pattern forinstance has a component in the transverse direction (cd-direction) ofthe web, so that the web is elongatable in the machine direction. By useof the apparatus according to the invention, it is possible to providethe leg portions 172 of the diaper, as is indicated in FIG. 20, withincreased extensibility. Preferably, an elastic element is comprisedbetween the topsheet and the backsheet in its relaxed state in the areasof deformation. Prior to contacting the web with the corrugated members170, 171, the web 1 can not be substantially elongated, and can hence betransported without the need of a vacuum conveyor. After contacting theweb with the corrugated members 170, 171, the areas of the web 1 inwhich the elastics are located are activated, and become elasticallyextensible.

The physical deformation can also be applied in the longitudinaldirection of the web 1, for instance in the area of the side panels 158,or the waist areas, 173, 175 as shown in FIG. 20.

A known method for applying physical deformations to impart extensiblityto a web is commonly referred to as "ringrolling". Ringrolling involvespassing the moving web between the nip of two rollers that are providedwith circumferential corrugations. The axes of the rollers extend in thecross-machine direction of the web. Another form of "ringrolling"involves the use of fiat corrugated members, of the type shown in FIGS.19a and 19b of the present application. The above methods ofringrolling, as well as structures produced thereby have been describedin detail in U.S. Pat. No. 5,196,000 issued to Clear et al. on Mar. 23,1993; U.S. Pat. No. 5,167,897, issued to Weber et al. on Dec. 1, 1992;U.S. Pat. No. 5,156,793, issued to Buell et al. on Oct. 20, 1992, inparticular FIG. 5, in combination with the description, Column 20; andU.S. Pat. No. 5,143,679, issued to Weber et al. on Sep. 1, 1992.

The method and apparatus according to the invention allow slow-speeddeformation of the web 1. Hence the impact-times of the corrugatedmembers on the web can be longer so that the physical deformation can bebetter dimensionally controlled and the energy imparted to the web canbe more gradually distributed.

The apparatus according to the invention can be used to provide complexdeformation patterns to products of the type described in the abovepatents. The physical deformation imparted by the method and apparatusaccording to the invention, can be so configured to impart extensibilityto the whole of the absorbent product, such as the combined topsheet,backsheet and core, or to only portions thereof, such as to the lateralwings of a sanitary napkin as described in U.S. Pat. No. 4,687,478,issued to Van Tilburg on Aug. 18, 1987.

In FIG. 21, the web 1 is passed under an applicator 176 of absorbentgelling material, that is supplied to the applicator from a storagevessel 177. Applicators for dispensing particulate absorbent gellingmaterial to a web, in particular powder spray guns, have been describedin U.S. Pat. No. 4,543,274, issued to Mulder et al. on Sep. 24, 1985 andEuropean Patent EP-B-0 330 675. By accelerating the web 1 with respectto the applicator 176, the concentration of absorbent gelling materialin the core can be varied in the machine direction, at a constant rateof deposition by the applicator.

I claim:
 1. Method of making an absorbent article (144), the articlecomprising a liquid-pervious topsheet (121, 145), a liquid imperviousbacksheet (123, 146) and an absorbent core (120, 147) interposed betweenthe topsheet and the backsheet, the method comprising the steps of:a)feeding a web (1), comprising the topsheet (121, 145) the backsheet(123, 146) or the core (120, 147) or a combination thereof along astationary frame (35), along an upstream trajectory (3), a downstreamtrajectory (5), and an intermediate trajectory (7a, 7b, 7c) comprisedbetween the upstream trajectory and the downstream trajectory, the web(1) having along the upstream trajectory (3) and along the downstreamtrajectory (5) a substantially constant speed of transport, the upstreamand the downstream trajectory (3, 5) being substantially stationaryrelative to the frame (35), b) running the web (1) along an upstream anda downstream guide roller (9, 11) that are translationally stationaryrelative to the frame (35) and along an upstream and a downstreamtransport roller (13, 15) that are periodically displaced, said upstreamand downstream transport rollers (13, 15) are connected to adisplacement balancing means (77), the transport rollers and thedisplacement balancing means being reciprocated, a combined center ofmass of the displacement balancing means and the transport roller beingmaintained in a stationary position such that:a first section (7a) ofthe intermediate trajectory (7a, 7b, 7c) of the web (1) extends betweenthe upstream guide roller (9) and the upstream transport roller (13), asecond section (7b) of the intermediate trajectory (7a, 7b, 7c) extendsbetween the upstream guide roller (9) and the downstream guide roller(11) or between the upstream transport roller (13) and the downstreamtransport roller (15), and a third section 7c of the intermediatetrajectory (7a, 7b, 7c) extends between the downstream guide roller (11)and the downstream transport roller (15), the first section (7a) and thethird section (7c) of the intermediate trajectory (7a, 7b, 7c) of theweb, (1) being parallel to the second section (7b) of the intermediatetrajectory, c) periodically displacing the transport rollers (13, 15)relative to the guide rollers (9, 11) around a stationary equilibriumposition (39) in a direction substantially parallel to the secondsection (7b) of the intermediate trajectory of the web (1), whilekeeping constant a length of the intermediate trajectory (7a, 7b, 7c)and while keeping constant a length of the second section (7b) of theintermediate trajectory and d) rotating the transport rollers (13, 15)such that strain exerted on the web (1) in running the web past thetransport rollers (13, 15) is not substantially larger than strainexerted on the web by inertia forces acting on the web (1).
 2. Methodaccording to claim 1, wherein the guide rollers (9,11) are rotated. 3.Method according to claim 1, the guide rollers (9,11) and the transportrollers (12,15) being driven by a drive member (50) which is coupledwith the guide rollers and the transport rollers to form a closed loop,a part of which extends parallel to the intermediate trajectory (7a, 7b,7c), the drive member (50) being driven at a constant speed.
 4. Methodaccording to claim 1, the transport rollers (13,15) being connected to arotation-balancing means (63, 63'), such that variations in torqueexerted by the transport rollers (13,15) are reduced.
 5. Methodaccording to claim 4, the method further comprising driving thetransport rollers (13,15) and the rotation-balancing means (63, 63') incombination, at constant torque.
 6. Method of making an absorbentarticle (144), the article comprising a liquid-pervious topsheet (121,145), a liquid impervious backsheet (123, 146) and an absorbent core(120, 147) interposed between the topsheet and the backsheet, the methodcomprising the steps of:a) feeding a web (1), comprising the topsheet(121, 145) the backsheet (123, 146) or the core (120, 147) or acombination thereof along a stationary frame (35), along an upstreamtrajectory (3), a downstream trajectory (5), and an intermediatetrajectory (7a, 7b, 7c) comprised between the upstream trajectory andthe downstream trajectory, the web (1) having along the upstreamtrajectory (3) and along the downstream trajectory (5) a substantiallyconstant speed of transport, the upstream and the downstream trajectory(3, 5) being substantially stationary relative to the frame (35), b)running the web (1) along an upstream and a downstream guide roller (9,11) that are translationally stationary relative to the frame (35) andalong an upstream and a downstream transport roller (13, 15), whereinthe periodically displaceable transport rollers (13, 15) are connectedto a displacement balancing means (77), such that:a first section (7b)of the intermediate trajectory (7a, 7b, 7c) of the web (1) extendsbetween the upstream guide roller (9) and the upstream transport roller(13), a second section (76) of the intermediate trajectory (7a, 7b, 7c)extends between the upstream guide roller (9) and the downstream guideroller (11) or between the upstream transport roller (13) and thedownstream transport roller (15), and a third section (7c) of theintermediate trajectory (7a, 7b, 7c) extends between the downstreamguide roller (11) and the downstream transport roller (13), the firstsection (7a) and the third section (7c) of the intermediate trajectory(7a, 7b, 7c) of the web, (1) being parallel to the second section (7b)of the intermediate trajectory, c) periodically displacing the transportrollers (13, 15) relative to the guide rollers (9,11) around astationary equilibrium position (39) at a frequency of between 1 Hz and100 Hz, in a direction substantially parallel to the second section (7b)of the intermediate trajectory (7a, 7b, 7c) of the web (1), whilekeeping constant the length of the intermediate trajectory (7a, 7b, 7c)and while keeping constant the length of the second section (7b) of theintermediate trajectory, and d) moving the displacement-balancing means(77) so as to keep a combined center of mass of the transport rollers(13, 15) and the displacement balancing means (77) substantiallystationary.
 7. Method according to claims 1 or 6, wherein the periodicspeed at which the transport rollers (13, 15) are moved relative to theguide rollers (9, 11) has an amplitude of 1/(2n) times a speed oftransport, so that the second section (7b) of the intermediatetrajectory (7a, 7b, 7c) is periodically stationary with respect to theframe (35), wherein n is a natural member.
 8. Method according to claims1 or 6, the method including, for a part of the web that is locatedalong the second section (7b) of the intermediate trajectory (7a, 7b,7c), any of the following steps or combinations thereof:applying anadhesive to the web, applying a tape fastening system to the web,applying an absorbent gelling material to the web, applying a waistfeature to the web, applying a reinforcement strip to the web orimparting an increased extensibility to the web.
 9. Apparatus (2) formanufacturing an absorbent article (144), the article comprising aliquid-pervious topsheet (121, 145), a liquid impervious backsheet (123,146) and an absorbent core (120, 147) interposed between the topsheetand the backsheet, the apparatus comprising:a stationary frame (35), anupstream and a downstream guide roller (9, 11) connected to the frame(35) in a translationally stationary manner, each guide roller (9, 11)having an axis (19, 21), the axes (19, 21) being generally parallel, theguide rollers (9, 11) being rotatable around their axes (19, 21), therotational drive means (50, 51) a drive member (50) which is run alongguide rollers (9, 11) and the transport rollers (13, 15) to form aclosed loop, and a drive motor (51) driving the drive member (50) at aconstant speed and a constant direction of rotation, and upstream and adownstream rotatable, cylindrical transport roller (13, 15), the axes(25, 27) of which are generally parallel to the axes (19, 21) of theguide rollers (9, 11), the cylindrical surface of the upstream guideroller (9) and the upstream transport (134) roller being substantiallytangent to a first plane (29), the cylindrical surface of the downstreamguide roller (11) and the downstream transport roller (15) beingsubstantially tangent to a second plane (31) which is substantiallyparallel the first plane (29), and a circumferential surface of bothguide rollers (9, 11) or both transport rollers (13, 15) beingsubstantially tangent to a third plane (33) which is located at a spacedapart location from the first plane (29) and the second plane (31) andwhich is parallel thereto, translational drive means (36, 71) connectedto the frame (35) for periodically displacing the transport rollers (13,15) generally perpendicular to the axes (25, 27) of the transportrollers (13, 15), around an equilibrium position (39) located generallymidway between the axes (19, 21) of the guide rollers (9, 11), adistance between the axes (25, 27) of the transport rollers beingconstant, rotational drive means (50, 51) for rotating the transportrollers (13, 15) in synchronism with the displacement of the transportrollers, such that when a web (1) comprising the topsheet, thebacksheet, the core or any combination thereof, is run past thetransport members (13, 15), strain on the web (11) is not substantiallylarger than strain exerted on the web by inertia forces acting on theweb (1), and rotation balancing means (63, 63') for each transportroller (13, 15) a rotatable disc (65, 65')a phase of the rotationalspeed of which differs by 180°, or a whole multiple thereof from thephase of the rational speed of the transport rollers (13, 15), so thatthe transport rollers (13, 15) and the balancing means (63, 63') incombination can be rotated at a constant torque.
 10. Apparatus accordingto claim 9, the transport rollers (13,15) being connected to a sled (41)which is mounted on the frame (35) so as to be movable relative to theframe (35).
 11. Apparatus according to claim 10, the rotation-balancingmeans (63, 63') comprising for each transport roller (13, 15):twopulleys (67, 67', 69, 69') connected to a sled (41), one pulley (67,67') being driven by a respective transport roller (13, 15) and a belt(70, 70') fed around the circumference of a disc (65, 65') and aroundboth respective pulleys (67, 69, 67', 69') to form a closed loop. 12.Apparatus according to claim 11, the transport rollers (13, 15) beingconnected to a translation-balancing means (77) to maintain a generallyconstant position of a combined center of mass of the balancing means(77), the transport rollers (13, 15) and the sled (41).
 13. Apparatus(2) for manufacturing an absorbent article (144), the article comprisinga liquid-pervious topsheet (121, 145), a liquid impervious backsheet(123, 146) and an absorbent core (129, 147) interposed between thetopsheet (121, 145) and the backsheet (123, 146), the apparatuscomprising:a stationary frame (35), an upstream and a downstream guideroller (9, 11) which are connected to the frame (35) in atranslationally stationary manner, each guide roller (9, 11) having anaxis (19, 21), the axes (19, 21) being generally parallel, an upstreamand a downstream, rotatable, cylindrical transport roller (13, 15), theguide rollers being connected to a sled (41) which is translationallymounted on the frame (35) the axes (25, 27) of which are generallyparallel to the axes (19, 21) of the guide rollers (9, 11), thecylindrical surface of the upstream guide roller (9) and the upstreamtransport roller (13) being substantially tangent to a first plane (29),the cylindrical surface of the downstream guide roller (11) and thedownstream transport roller (15) being substantially tangent to a secondplane (31) which is substantially parallel to the first plane, and acircumferential surface of both guide rollers (9, 11) or both transportrollers (13, 15) being substantially tangent to a third plane (33) whichis located at a spaced apart location from the first plane (29) and thesecond plane (31) and which is parallel thereto, translational drivemeans (36, 71) connected to the sled (41) for periodically displacingthe transport rollers (13, 15) generally perpendicular to the axes (25,27) of the transport rollers, around an equilibrium position (39)located generally midway between the axes (19, 21) of the guide rollers(9, 11), the distance between the axes (25, 27) of the transport rollers(13, 15) being constant, and translation-balancing means (77) tomaintain a generally constant position of a center of mass of thebalancing means (77), the transport rollers (13, 15) and the sled (41).14. Apparatus (2) according to claims 9 or 13, wherein the first and thesecond plane (29,31) are coincident, a distance between the axes (25,27)of the transport rollers (13,15) being larger than a distance betweenthe axes (19,21) of the guide rollers (9,11) and wherein the transportrollers (13,15) are displaceable in a substantially straight line. 15.Apparatus according to claim 14, a distance between the axes (25,27) ofthe transport rollers being (13,15) smaller than a distance between theaxes (19,21) of the guide rollers, (9,11) and wherein the transportrollers. (13,15) are displace along a circular path.
 16. Apparatusaccording to claims 9 or 13, the sled (41) being suspended from theframe (35) by a suspension means (79,79') comprising two vertical arms(89,89'), a lower end (96,96') of each arm (79,79') being connected to arespective end of the sled (41), each vertical arm (89,89') being at itsupper end hingably connected to the frame (35).
 17. Apparatus accordingto claim 16, the upper end of each vertical arm (89,89') of thesuspension means (79,79')being connected in a hinging point (108) to afirst side of a transverse arm (93,93'), the transverse arm(93,93')being at a second side hingingly connected to the frame(35),each vertical arm (89,89') being hingably connected at its midpoint(97,97') to an upper end of a further vertical arm (86,86') that extendsgenerally parallel to the vertical arm (89,89') and has a length ofgenerally half of the length of the vertical arm (89, 89'), a lower endof the further vertical arm (86, 86') being hingably connected to theframe (35).
 18. Apparatus according to claims 9 or 13, the translationaldrive means (36, 71) comprising a reciprocatable cantilever (71),connected to the frame (35) in a pivot point (75), the cantilever (71)being connected to the sled (41) in a drive point (73).
 19. Apparatusaccording to claim 18, a distance between the pivot point (75) and thedrive point (73) being adjustable.
 20. Apparatus according to claims 9or 13, the apparatus including applicator means (38,38') which arepositionally stationary relative to the frame (35), the applicator means(38, 38') including any of the following or combinations thereof:an glueapplicator for applying an adhesive to a web (1), gripper means, inparticular a vacuum gripper, for applying a tape fastening system, awaist feature or a reinforcement strip to a web (1), dispensing means(176) for applying an absorbent gelling material to a web (1), orcorrugated deformation members (170, 171) for imparting an increasedextensibility to a web (1) or a part thereof.